The present invention relates generally to plumbing systems or devices utilizing water connections. More particularly, this invention pertains to general appliances that utilize water connections that are subject to breakage. The invention has utility in applications such as washing machines, water heaters, ice makers, dishwashers and other appliances associated with water overflow or spillage. The application claimed herein is the only system using an ionizing water sensor. All other known or patented devices use systems that are more complex or expensive.
A basic understanding of chemical compositions and electrolytes is helpful in understanding the present invention. Water is an excellent solvent for many compounds. Some compounds dissolve in water as molecules while electrolytes dissociate and dissolve as charged species called ions. Some dissolved compound solutions conduct electricity better than others do, and can be rated on a scaling system. The scaling system includes strong electrolytes, weak electrolytes, and non-electrolytes. These Electrolytes are compounds which dissolve in water to produce solutions that conduct an electric current. A strong electrolyte conducts electricity very well. A weak electrolyte conducts electricity, but not very well. A non-electrolyte does not conduct electricity at all.
Strong electrolytes conduct electricity very well and ionize almost one hundred percent (100%). Most of the salts are in the strong electrolyte category. Examples of strong electrolytes include: HCl, HBr, HI, HNO3, HClO4, H2SO4, HClO3, LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. There are three common ways in which strong electrolyte conductor can be classified. These are as follows (1) creating an electrolyte by dissolving salts in a solvent by breaking the salt up into its ions; (2) use an acid to give off H+ ions; and (3) use a base to give off OH ions to allow for a good flow of electricity through the solution.
Strong acids are also strong electrolytes. The hydroxides of Groups I and II are considered strong bases and are also strong electrolytes. In addition, most other ionic compounds are strong electrolytes. Generally, the halides and cyanides of “heavy metals” are weak electrolytes and most organic compounds are nonelectrolytes. Some exceptions to he organic compounds are organic acids and bases.
Weak electrolytes conduct electricity a little and are only partially ionized. Most of the acids and bases are in this category. Weak electrolytes include both weak acids and weak bases. A weak acid is much like a strong acid because it produces H+ ions, but the difference is that a weak acid only partially dissociates. Partially dissociating means that only a small percentage of the acid gives off the H+ ions. Weak bases release OH− ions instead of H+ ions.
Non-electrolytes do not conduct electricity and do not ionize. A good example of a non-electrolyte is water. Additional non-Electrolytes are substances that will dissolve in water, but do not produce any ions and therefore do not conduct electricity. For example, sugar will dissolve in water, but will not produce ions. Thus there is nothing to transfer electricity through the solution.
In general, the difference between strong and weak electrolytes is the extent to which the ionic compounds dissociate into ions when placed in water. The greater the amount of dissociation, the greater the electrical conductance of the solution. The strong electrolytes are usually considered to be one hundred percent (100%) dissociated, especially in dilute solutions, and weak electrolytes are usually dissociated less than ten percent (<10%).
This basic chemical information is used in the present invention in combination with a water system. The large majority of commercially feasible water sensors are of the electrical capacitance style detection devices. The devices continuously supply a known low voltage to a pair of electrodes and a return voltage is transmitted back. The return voltage is measured to see if a closed circuit has occurred representing the presence of water. This closed circuit then energizes a horn, light, shut off valve, or a combination of the above. These devices utilize low voltages as a safety feature and thus, these devices can be fooled by varying trace levels of elements in the water, such as calcium and iron. In addition, main power supply fluctuations and electrical noise will also affect the reliability of these devices.
Several United States Patents have been directed towards water detection systems. These patents include U.S. Pat. No. 2,432,367, issued to Anderson on Sep. 23, 1943; U.S. Pat. No. 2,726,294, issued to Kroening, et al on Jan. 30, 1951; U.S. Pat. No. 3,770,002, issued to Brown on Nov. 6, 1973; U.S. Pat. No. 3,847,547, issued to Delgendre, et al on Nov. 12, 1974; U.S. Pat. No. 3,872,419, issued to Groves, et al on Mar. 18, 1975; U.S. Pat. No. 4,163,449, issued to Regal on Aug. 7, 1979; U.S. Pat. No. 4,418,712 issued to Braley on Dec. 6, 1983; U.S. Pat. No. 4,489,603, issued to Fukami, et al on Dec. 25, 1984; U.S. Pat. No. 4,845,472, issued to Gordon on Jul. 4, 1989; U.S. Pat. No. 5,188,143 issued to Krebs on Feb. 23, 1993; U.S. Pat. No. 5,190,069 issued to Richards on Mar. 2, 1993; U.S. Pat. No. 5,240,022 issued to Franklin on Aug. 31, 1993; U.S. Pat. No. 5,334,973, issued to Furr on Aug. 2, 1994; U.S. Pat. No. 5,844,492 issued to Bufflin, Sr. on Dec. 1, 1998; and U.S. Pat. No. 5,877,689 issued to D'Amico on Mar. 2, 1999. The following is a brief discussion of the most relevant of these patents.
U.S. Pat. No. 2,432,367 issued to Anderson on Dec. 9, 1947 discloses a leak detector. This specification discloses the use of a water absorbent material which expands to close the contacts of an electrical circuit for generating a water detection signal. In this specification, it is noted that the electrical contacts should be maintained separately from the absorbent material and the fluid that is to be detected.
U.S. Pat. No. 3,847,547 issued to Delgendre et al. on Nov. 12, 1974, discloses a PROCESS AND APPARATUS FOR DETECTING OF THE PRESENCE OF A LIQUID. This specification describes the use of a chemical reaction, such as a pyrotechnical composition with the absorption of water for closing an electrical circuit. Specifically, the invention teaches the production of heat to generate an electrically conducting deposit in the zone situated between the two electrodes for closing an electrical circuit. The invention also teaches the melting of fusible conducting wire in order to open an electrical circuit. These processes are activated by a chemical reaction when water is introduced into the sensor.
U.S. Pat. No. 4,418,712 issued to Braley on Dec. 6, 1983 discloses an overflow control system for use with appliances such as washing machines. The device has a sensor mechanism that senses any spilled water beneath the machine. Upon water being sensed, electrical circuitry is activated that sounds an alarm and also shuts off the washing machine so that the machine will not continue to pump water through its exit pipe and into the drain stand. This device is designed to avoid problems associated with overflows because of clogging of the drain lines but does not address the need to shut off water coming into the machine.
U.S. Pat. No. 4,489,603 issued to Fukami et al. on Dec. 25, 1984 discloses a moisture sensitive element. In column 1, lines 39–45, this patent specification describes the use of prior art humidity detection systems and references the “ionic conduction through moisture absorption” for humidity sensors. However, as noted by this description of the prior art systems, the prior art units are directed towards humidistats and not switches.
U.S. Pat. No. 5,190,069 issued to Richards on Mar. 2, 1993 discloses a leak detection apparatus for monitoring leakage for household water systems. The system includes a pair of spaced wires imbedded in an insulating tape. The tape can be wrapped about water supply lines and if there is a leakage, the spaced wires will be connected and activate a servo to turn off a supply valve and/or sound an alarm.
U.S. Pat. No. 5,240,022 issued to Franklin on Aug. 31, 1993 discloses an automatic shut off valve system for installation in the water supply line of a hot water heater. The devise includes a sensor to detect leakage electrically by sensing moisture beneath the hot water heater and in response to the sensing of moisture, the device uses a valve system for shutting off the supply line to the hot water heater. The device of this patent is best illustrated in FIG. 2, showing a leak detection module 17 which activates the shut off valve 1 which is activated in response to the module 17 sensing moisture beneath the hot water heater. The cut off valve 1 is inserted in the supply pipe via the pipe fittings 2 and 3 as can be seen in FIG. 1.
U.S. Pat. No. 5,334,973 issued to Furr on Aug. 2, 1994 discloses a leak detection and a shut-off apparatus. This patent describes a sensor 127 which utilizes a blotter or non-conductive material that becomes conductive when it absorbs moisture. The blotter is contained within a copper skin such that it allows a capacitance current to flow when water is detected.
U.S. Pat. No. 5,877,689 issued to D'Amico on Mar. 2, 1999. The D'Amico patent discloses a system quite similar to that of the Franklin patent. There is shown a water appliance 12 having a supply pipe 14 which allows water to be supplied to the appliance. In this particular case, the appliance is gas powered and has a gas supply conduit 16 for transmitting gas from the gas source to the machine. Situated below the water appliance is a water sensor 34. When the water sensor 34 detects water in the pan beneath the appliance, it is activated to both shut off the water supply to the appliance and shut off the gas supply to the appliance so that the appliance will not burn out once the water is drained from the appliance.
These systems fail to disclose adequate systems for efficient, low-cost water detection systems for household appliances and other water utilizing systems. Therefore, because of the inadequate systems presently used in the prior art an improved water detection system is required. The present system is designed to provide a low-cost, basic, reliable, protection system that is not susceptible to voltage fluctuations or electrical noise and provides an affordable alternative for the consumer.